C#

using System;
using System.Collections.Generic;
using Newtonsoft.Json;

namespace study_dictionary
{
    class Program
    {
        static void Main(string[] args)
        {
            DictionaryStudy();
        }

        /// <summary>
        /// ContainsKey：     确定 Dictionary是否包含指定的键。
        /// ContainsValue：   确定 Dictionary是否包含特定值。
        /// TryAdd：          存在添加不成功
        /// </summary>
        static void DictionaryStudy() {
            //Dictionary<int, string> dictionaryTest = new Dictionary<int, string>() { { 1, "gyg" }, { 2, "gmd" } };//初始化不推荐

            Dictionary<int, string> dictionaryTest = new Dictionary<int, string>();

            dictionaryTest.Clear();//清空所有的键值

            if (!dictionaryTest.ContainsKey(1))//防止报异常
            {
                dictionaryTest.Add(1, "gyg");
            }
            bool result = dictionaryTest.TryAdd(1, "gxh");//存在添加不成功
            Console.WriteLine("TryAdd：" + result);
            //dictionaryTest.Add(1, "gmd");//这样会报异常

            Console.WriteLine(dictionaryTest[1]);//取值

            dictionaryTest[1] = "gmd";//索引方式赋值，没有则新增，有则修改
            dictionaryTest[2] = "gyg";

            dictionaryTest.Remove(2);//根据键删除

            dictionaryTest.Add(3, "gxy");
            dictionaryTest.Add(4, "gxy");

            Console.WriteLine("count：" + dictionaryTest.Count);

            //遍历键值对
            foreach (var kvp in dictionaryTest)//var => KeyValuePair<int, string>
            {
                Console.WriteLine("key：" + kvp.Key + "-value：" + kvp.Value);
            }

            //遍历键
            //dictionaryTest.Keys => Dictionary<int, string>.KeyCollection
            foreach (int key in dictionaryTest.Keys)
            {
                Console.WriteLine("key：" + key);
            }

            //遍历值
            Dictionary<int, string>.ValueCollection vc = dictionaryTest.Values;
            foreach (string value in vc)
            {
                Console.WriteLine("value：" + value);
            }

            string json = JsonConvert.SerializeObject(dictionaryTest);

            Console.WriteLine("json字符串：" + json);

            
            //Console.WriteLine(dictionaryTest[5]);//不存在的键会报异常
            dictionaryTest.TryGetValue(5, out string value1);
            Console.WriteLine("TryGetValue：" + value1);
            
        }
    }
}